I used TSMuxer to create the folder structure with split m2ts files. I also used AVCHDMe to rename non-compatible filenames to 8.3 format.

On copying the folder across to the memory stick (actually an 8GB SD card with a USB adapter) I discovered that it wouldn't fit - 8GB was actually about 7.45GiB, whereas a DVD9 is 7.95GiB. (I thought memory always used "binary" prefixes, unlike hard drives, but what the hell.)

I might have been able to make it fit if I'd taken out some audio tracks when remuxing. However, on checking the files that I had copied over last week I found a complete m2ts file, as well as two corrupted files and what appeared to be a transcode. The m2ts file on the PS3 hard drive was complete and (I think) untouched, so I watched that.

For the future, sharing the virtual drive root in PS3 Media Server was probably the wrong thing to do, and I should have just shared the stream folder or even the m2ts file itself.